2 * Copyright (c) 2002 Networks Associates Technology, Inc.
5 * This software was developed for the FreeBSD Project by ThinkSec AS and
6 * NAI Labs, the Security Research Division of Network Associates, Inc.
7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
8 * DARPA CHATS research program.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
35 * Permission to use, copy, modify, and distribute this software for any
36 * purpose with or without fee is hereby granted, provided that the above
37 * copyright notice and this permission notice appear in all copies.
39 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
40 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
41 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
42 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
43 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
44 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
45 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
48 /* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */
52 #include <sys/types.h>
63 #if defined(HAVE_SECURITY_PAM_APPL_H)
64 #include <security/pam_appl.h>
65 #elif defined (HAVE_PAM_PAM_APPL_H)
66 #include <pam/pam_appl.h>
69 #if !defined(SSHD_PAM_SERVICE)
70 extern char *__progname;
71 # define SSHD_PAM_SERVICE __progname
74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
75 #ifdef PAM_SUN_CODEBASE
76 # define sshpam_const /* Solaris, HP-UX, SunOS */
78 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */
81 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */
82 #ifdef PAM_SUN_CODEBASE
83 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member)
85 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member)
101 #include "auth-options.h"
105 #include "monitor_wrap.h"
106 #include "blacklist_client.h"
108 extern ServerOptions options;
109 extern Buffer loginmsg;
110 extern u_int utmp_len;
112 /* so we don't silently change behaviour */
113 #ifdef USE_POSIX_THREADS
114 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
118 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
119 * and generally a bad idea. Use at own risk and do not expect support if
122 #ifdef UNSUPPORTED_POSIX_THREADS_HACK
125 * Avoid namespace clash when *not* using pthreads for systems *with*
126 * pthreads, which unconditionally define pthread_t via sys/types.h
129 typedef pthread_t sp_pthread_t;
131 typedef pid_t sp_pthread_t;
135 sp_pthread_t pam_thread;
141 static void sshpam_free_ctx(void *);
142 static struct pam_ctxt *cleanup_ctxt;
144 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
146 * Simulate threads with processes.
149 static int sshpam_thread_status = -1;
150 static mysig_t sshpam_oldsig;
153 sshpam_sigchld_handler(int sig)
155 signal(SIGCHLD, SIG_DFL);
156 if (cleanup_ctxt == NULL)
157 return; /* handler called after PAM cleanup, shouldn't happen */
158 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
160 /* PAM thread has not exitted, privsep slave must have */
161 kill(cleanup_ctxt->pam_thread, SIGTERM);
162 while (waitpid(cleanup_ctxt->pam_thread,
163 &sshpam_thread_status, 0) == -1) {
169 if (WIFSIGNALED(sshpam_thread_status) &&
170 WTERMSIG(sshpam_thread_status) == SIGTERM)
171 return; /* terminated by pthread_cancel */
172 if (!WIFEXITED(sshpam_thread_status))
173 sigdie("PAM: authentication thread exited unexpectedly");
174 if (WEXITSTATUS(sshpam_thread_status) != 0)
175 sigdie("PAM: authentication thread exited uncleanly");
180 pthread_exit(void *value)
187 pthread_create(sp_pthread_t *thread, const void *attr,
188 void *(*thread_start)(void *), void *arg)
191 struct pam_ctxt *ctx = arg;
193 sshpam_thread_status = -1;
194 switch ((pid = fork())) {
196 error("fork(): %s", strerror(errno));
199 close(ctx->pam_psock);
205 close(ctx->pam_csock);
207 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
213 pthread_cancel(sp_pthread_t thread)
215 signal(SIGCHLD, sshpam_oldsig);
216 return (kill(thread, SIGTERM));
221 pthread_join(sp_pthread_t thread, void **value)
225 if (sshpam_thread_status != -1)
226 return (sshpam_thread_status);
227 signal(SIGCHLD, sshpam_oldsig);
228 while (waitpid(thread, &status, 0) == -1) {
231 fatal("%s: waitpid: %s", __func__, strerror(errno));
238 static pam_handle_t *sshpam_handle = NULL;
239 static int sshpam_err = 0;
240 static int sshpam_authenticated = 0;
241 static int sshpam_session_open = 0;
242 static int sshpam_cred_established = 0;
243 static int sshpam_account_status = -1;
244 static int sshpam_maxtries_reached = 0;
245 static char **sshpam_env = NULL;
246 static Authctxt *sshpam_authctxt = NULL;
247 static const char *sshpam_password = NULL;
249 /* Some PAM implementations don't implement this */
250 #ifndef HAVE_PAM_GETENVLIST
252 pam_getenvlist(pam_handle_t *pamh)
255 * XXX - If necessary, we can still support envrionment passing
256 * for platforms without pam_getenvlist by searching for known
257 * env vars (e.g. KRB5CCNAME) from the PAM environment.
264 * Some platforms, notably Solaris, do not enforce password complexity
265 * rules during pam_chauthtok() if the real uid of the calling process
266 * is 0, on the assumption that it's being called by "passwd" run by root.
267 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
270 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
272 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
276 if (sshpam_authctxt == NULL)
277 fatal("PAM: sshpam_authctxt not initialized");
278 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
279 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
280 result = pam_chauthtok(pamh, flags);
281 if (setreuid(0, -1) == -1)
282 fatal("%s: setreuid failed: %s", __func__, strerror(errno));
285 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b)))
289 sshpam_password_change_required(int reqd)
291 extern struct sshauthopt *auth_opts;
292 static int saved_port, saved_agent, saved_x11;
294 debug3("%s %d", __func__, reqd);
295 if (sshpam_authctxt == NULL)
296 fatal("%s: PAM authctxt not initialized", __func__);
297 sshpam_authctxt->force_pwchange = reqd;
299 saved_port = auth_opts->permit_port_forwarding_flag;
300 saved_agent = auth_opts->permit_agent_forwarding_flag;
301 saved_x11 = auth_opts->permit_x11_forwarding_flag;
302 auth_opts->permit_port_forwarding_flag = 0;
303 auth_opts->permit_agent_forwarding_flag = 0;
304 auth_opts->permit_x11_forwarding_flag = 0;
307 auth_opts->permit_port_forwarding_flag = saved_port;
309 auth_opts->permit_agent_forwarding_flag = saved_agent;
311 auth_opts->permit_x11_forwarding_flag = saved_x11;
315 /* Import regular and PAM environment from subprocess */
317 import_environments(Buffer *b)
323 debug3("PAM: %s entering", __func__);
325 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
326 /* Import variables set by do_pam_account */
327 sshpam_account_status = buffer_get_int(b);
328 sshpam_password_change_required(buffer_get_int(b));
330 /* Import environment from subprocess */
331 num_env = buffer_get_int(b);
333 fatal("%s: received %u environment variables, expected <= 1024",
335 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env));
336 debug3("PAM: num env strings %d", num_env);
337 for(i = 0; i < num_env; i++)
338 sshpam_env[i] = buffer_get_string(b, NULL);
340 sshpam_env[num_env] = NULL;
342 /* Import PAM environment from subprocess */
343 num_env = buffer_get_int(b);
344 debug("PAM: num PAM env strings %d", num_env);
345 for(i = 0; i < num_env; i++) {
346 env = buffer_get_string(b, NULL);
348 #ifdef HAVE_PAM_PUTENV
349 /* Errors are not fatal here */
350 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
351 error("PAM: pam_putenv: %s",
352 pam_strerror(sshpam_handle, sshpam_err));
360 * Conversation function for authentication thread.
363 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
364 struct pam_response **resp, void *data)
367 struct pam_ctxt *ctxt;
368 struct pam_response *reply;
371 debug3("PAM: %s entering, %d messages", __func__, n);
375 error("PAM: conversation function passed a null context");
376 return (PAM_CONV_ERR);
379 if (n <= 0 || n > PAM_MAX_NUM_MSG)
380 return (PAM_CONV_ERR);
382 if ((reply = calloc(n, sizeof(*reply))) == NULL)
383 return (PAM_CONV_ERR);
385 buffer_init(&buffer);
386 for (i = 0; i < n; ++i) {
387 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
388 case PAM_PROMPT_ECHO_OFF:
389 case PAM_PROMPT_ECHO_ON:
390 buffer_put_cstring(&buffer,
391 PAM_MSG_MEMBER(msg, i, msg));
392 if (ssh_msg_send(ctxt->pam_csock,
393 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
395 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
397 if (buffer_get_char(&buffer) != PAM_AUTHTOK)
399 reply[i].resp = buffer_get_string(&buffer, NULL);
403 buffer_put_cstring(&buffer,
404 PAM_MSG_MEMBER(msg, i, msg));
405 if (ssh_msg_send(ctxt->pam_csock,
406 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
412 buffer_clear(&buffer);
414 buffer_free(&buffer);
416 return (PAM_SUCCESS);
419 for(i = 0; i < n; i++) {
423 buffer_free(&buffer);
424 return (PAM_CONV_ERR);
428 * Authentication thread.
431 sshpam_thread(void *ctxtp)
433 struct pam_ctxt *ctxt = ctxtp;
435 struct pam_conv sshpam_conv;
436 int flags = (options.permit_empty_passwd == 0 ?
437 PAM_DISALLOW_NULL_AUTHTOK : 0);
438 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
439 extern char **environ;
442 const char *pam_user;
443 const char **ptr_pam_user = &pam_user;
444 char *tz = getenv("TZ");
446 sshpam_err = pam_get_item(sshpam_handle, PAM_USER,
447 (sshpam_const void **)ptr_pam_user);
448 if (sshpam_err != PAM_SUCCESS)
453 if (setenv("TZ", tz, 1) == -1)
454 error("PAM: could not set TZ environment: %s",
457 if (sshpam_authctxt != NULL) {
458 setproctitle("%s [pam]",
459 sshpam_authctxt->valid ? pam_user : "unknown");
463 sshpam_conv.conv = sshpam_thread_conv;
464 sshpam_conv.appdata_ptr = ctxt;
466 if (sshpam_authctxt == NULL)
467 fatal("%s: PAM authctxt not initialized", __func__);
469 buffer_init(&buffer);
470 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
471 (const void *)&sshpam_conv);
472 if (sshpam_err != PAM_SUCCESS)
474 sshpam_err = pam_authenticate(sshpam_handle, flags);
475 if (sshpam_err == PAM_MAXTRIES)
476 sshpam_set_maxtries_reached(1);
477 if (sshpam_err != PAM_SUCCESS)
480 if (!do_pam_account()) {
481 sshpam_err = PAM_ACCT_EXPIRED;
484 if (sshpam_authctxt->force_pwchange) {
485 sshpam_err = pam_chauthtok(sshpam_handle,
486 PAM_CHANGE_EXPIRED_AUTHTOK);
487 if (sshpam_err != PAM_SUCCESS)
489 sshpam_password_change_required(0);
492 buffer_put_cstring(&buffer, "OK");
494 #ifndef UNSUPPORTED_POSIX_THREADS_HACK
495 /* Export variables set by do_pam_account */
496 buffer_put_int(&buffer, sshpam_account_status);
497 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);
499 /* Export any environment strings set in child */
500 for(i = 0; environ[i] != NULL; i++)
502 buffer_put_int(&buffer, i);
503 for(i = 0; environ[i] != NULL; i++)
504 buffer_put_cstring(&buffer, environ[i]);
506 /* Export any environment strings set by PAM in child */
507 env_from_pam = pam_getenvlist(sshpam_handle);
508 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
510 buffer_put_int(&buffer, i);
511 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
512 buffer_put_cstring(&buffer, env_from_pam[i]);
513 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */
515 /* XXX - can't do much about an error here */
516 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
517 buffer_free(&buffer);
521 buffer_put_cstring(&buffer,
522 pam_strerror(sshpam_handle, sshpam_err));
523 /* XXX - can't do much about an error here */
524 if (sshpam_err == PAM_ACCT_EXPIRED)
525 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer);
526 else if (sshpam_maxtries_reached)
527 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, &buffer);
529 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
530 buffer_free(&buffer);
533 return (NULL); /* Avoid warning for non-pthread case */
537 sshpam_thread_cleanup(void)
539 struct pam_ctxt *ctxt = cleanup_ctxt;
541 debug3("PAM: %s entering", __func__);
542 if (ctxt != NULL && ctxt->pam_thread != 0) {
543 pthread_cancel(ctxt->pam_thread);
544 pthread_join(ctxt->pam_thread, NULL);
545 close(ctxt->pam_psock);
546 close(ctxt->pam_csock);
547 memset(ctxt, 0, sizeof(*ctxt));
553 sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
554 struct pam_response **resp, void *data)
556 debug3("PAM: %s entering, %d messages", __func__, n);
557 return (PAM_CONV_ERR);
560 static struct pam_conv null_conv = { sshpam_null_conv, NULL };
563 sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
564 struct pam_response **resp, void *data)
566 struct pam_response *reply;
570 debug3("PAM: %s called with %d messages", __func__, n);
573 if (n <= 0 || n > PAM_MAX_NUM_MSG)
574 return (PAM_CONV_ERR);
576 if ((reply = calloc(n, sizeof(*reply))) == NULL)
577 return (PAM_CONV_ERR);
579 for (i = 0; i < n; ++i) {
580 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
583 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
584 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
585 buffer_append(&loginmsg, "\n", 1 );
586 reply[i].resp_retcode = PAM_SUCCESS;
593 return (PAM_SUCCESS);
596 for(i = 0; i < n; i++) {
600 return (PAM_CONV_ERR);
603 static struct pam_conv store_conv = { sshpam_store_conv, NULL };
608 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor()))
610 debug("PAM: cleanup");
611 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
612 if (sshpam_session_open) {
613 debug("PAM: closing session");
614 pam_close_session(sshpam_handle, PAM_SILENT);
615 sshpam_session_open = 0;
617 if (sshpam_cred_established) {
618 debug("PAM: deleting credentials");
619 pam_setcred(sshpam_handle, PAM_DELETE_CRED);
620 sshpam_cred_established = 0;
622 sshpam_authenticated = 0;
623 pam_end(sshpam_handle, sshpam_err);
624 sshpam_handle = NULL;
628 sshpam_init(Authctxt *authctxt)
630 const char *pam_rhost, *pam_user, *user = authctxt->user;
631 const char **ptr_pam_user = &pam_user;
632 struct ssh *ssh = active_state; /* XXX */
634 if (sshpam_handle != NULL) {
635 /* We already have a PAM context; check if the user matches */
636 sshpam_err = pam_get_item(sshpam_handle,
637 PAM_USER, (sshpam_const void **)ptr_pam_user);
638 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
640 pam_end(sshpam_handle, sshpam_err);
641 sshpam_handle = NULL;
643 debug("PAM: initializing for \"%s\"", user);
645 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
646 sshpam_authctxt = authctxt;
648 if (sshpam_err != PAM_SUCCESS) {
649 pam_end(sshpam_handle, sshpam_err);
650 sshpam_handle = NULL;
653 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns);
654 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
655 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
656 if (sshpam_err != PAM_SUCCESS) {
657 pam_end(sshpam_handle, sshpam_err);
658 sshpam_handle = NULL;
661 #ifdef PAM_TTY_KLUDGE
663 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
664 * sshd doesn't set the tty until too late in the auth process and
665 * may not even set one (for tty-less connections)
667 debug("PAM: setting PAM_TTY to \"ssh\"");
668 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
669 if (sshpam_err != PAM_SUCCESS) {
670 pam_end(sshpam_handle, sshpam_err);
671 sshpam_handle = NULL;
679 sshpam_init_ctx(Authctxt *authctxt)
681 struct pam_ctxt *ctxt;
684 debug3("PAM: %s entering", __func__);
686 * Refuse to start if we don't have PAM enabled or do_pam_account
687 * has previously failed.
689 if (!options.use_pam || sshpam_account_status == 0)
693 if (sshpam_init(authctxt) == -1) {
694 error("PAM: initialization failed");
698 ctxt = xcalloc(1, sizeof *ctxt);
700 /* Start the authentication thread */
701 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
702 error("PAM: failed create sockets: %s", strerror(errno));
706 ctxt->pam_psock = socks[0];
707 ctxt->pam_csock = socks[1];
708 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
709 error("PAM: failed to start authentication thread: %s",
721 sshpam_query(void *ctx, char **name, char **info,
722 u_int *num, char ***prompts, u_int **echo_on)
724 struct ssh *ssh = active_state; /* XXX */
726 struct pam_ctxt *ctxt = ctx;
732 debug3("PAM: %s entering", __func__);
733 buffer_init(&buffer);
736 *prompts = xmalloc(sizeof(char *));
739 *echo_on = xmalloc(sizeof(u_int));
740 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
741 type = buffer_get_char(&buffer);
742 msg = buffer_get_string(&buffer, NULL);
745 case PAM_PROMPT_ECHO_ON:
746 case PAM_PROMPT_ECHO_OFF:
748 len = plen + mlen + 1;
749 **prompts = xreallocarray(**prompts, 1, len);
750 strlcpy(**prompts + plen, msg, len - plen);
752 **echo_on = (type == PAM_PROMPT_ECHO_ON);
757 /* accumulate messages */
758 len = plen + mlen + 2;
759 **prompts = xreallocarray(**prompts, 1, len);
760 strlcpy(**prompts + plen, msg, len - plen);
762 strlcat(**prompts + plen, "\n", len - plen);
766 case PAM_ACCT_EXPIRED:
768 if (type == PAM_ACCT_EXPIRED)
769 sshpam_account_status = 0;
770 if (type == PAM_MAXTRIES)
771 sshpam_set_maxtries_reached(1);
774 debug3("PAM: %s", pam_strerror(sshpam_handle, type));
775 if (**prompts != NULL && strlen(**prompts) != 0) {
786 if (**prompts != NULL) {
787 /* drain any accumulated messages */
788 debug("PAM: %s", **prompts);
789 buffer_append(&loginmsg, **prompts,
794 if (type == PAM_SUCCESS) {
795 if (!sshpam_authctxt->valid ||
796 (sshpam_authctxt->pw->pw_uid == 0 &&
797 options.permit_root_login != PERMIT_YES))
798 fatal("Internal error: PAM auth "
799 "succeeded when it should have "
801 import_environments(&buffer);
808 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER,
809 sshpam_authctxt->user);
810 error("PAM: %s for %s%.100s from %.100s", msg,
811 sshpam_authctxt->valid ? "" : "illegal user ",
812 sshpam_authctxt->user,
813 auth_get_canonical_hostname(ssh, options.use_dns));
827 * Returns a junk password of identical length to that the user supplied.
828 * Used to mitigate timing attacks against crypt(3)/PAM stacks that
829 * vary processing time in proportion to password length.
832 fake_password(const char *wire_password)
834 const char junk[] = "\b\n\r\177INCORRECT";
836 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0;
839 fatal("%s: password length too long: %zu", __func__, l);
844 for (i = 0; i < l; i++)
845 ret[i] = junk[i % (sizeof(junk) - 1)];
850 /* XXX - see also comment in auth-chall.c:verify_response */
852 sshpam_respond(void *ctx, u_int num, char **resp)
855 struct pam_ctxt *ctxt = ctx;
858 debug2("PAM: %s entering, %u responses", __func__, num);
859 switch (ctxt->pam_done) {
861 sshpam_authenticated = 1;
869 error("PAM: expected one response, got %u", num);
872 buffer_init(&buffer);
873 if (sshpam_authctxt->valid &&
874 (sshpam_authctxt->pw->pw_uid != 0 ||
875 options.permit_root_login == PERMIT_YES))
876 buffer_put_cstring(&buffer, *resp);
878 fake = fake_password(*resp);
879 buffer_put_cstring(&buffer, fake);
882 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
883 buffer_free(&buffer);
886 buffer_free(&buffer);
891 sshpam_free_ctx(void *ctxtp)
893 struct pam_ctxt *ctxt = ctxtp;
895 debug3("PAM: %s entering", __func__);
896 sshpam_thread_cleanup();
899 * We don't call sshpam_cleanup() here because we may need the PAM
900 * handle at a later stage, e.g. when setting up a session. It's
901 * still on the cleanup list, so pam_end() *will* be called before
902 * the server process terminates.
906 KbdintDevice sshpam_device = {
914 KbdintDevice mm_sshpam_device = {
923 * This replaces auth-pam.c
926 start_pam(Authctxt *authctxt)
928 if (!options.use_pam)
929 fatal("PAM: initialisation requested when UsePAM=no");
931 if (sshpam_init(authctxt) == -1)
932 fatal("PAM: initialisation failed");
942 expose_authinfo(const char *caller)
947 * Expose authentication information to PAM.
948 * The enviornment variable is versioned. Please increment the
949 * version suffix if the format of session_info changes.
951 if (sshpam_authctxt->session_info == NULL)
952 auth_info = xstrdup("");
953 else if ((auth_info = sshbuf_dup_string(
954 sshpam_authctxt->session_info)) == NULL)
955 fatal("%s: sshbuf_dup_string failed", __func__);
957 debug2("%s: auth information in SSH_AUTH_INFO_0", caller);
958 do_pam_putenv("SSH_AUTH_INFO_0", auth_info);
965 debug("%s: called", __func__);
966 if (sshpam_account_status != -1)
967 return (sshpam_account_status);
969 expose_authinfo(__func__);
971 sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
972 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
973 pam_strerror(sshpam_handle, sshpam_err));
975 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
976 sshpam_account_status = 0;
977 return (sshpam_account_status);
980 if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
981 sshpam_password_change_required(1);
983 sshpam_account_status = 1;
984 return (sshpam_account_status);
988 do_pam_setcred(int init)
990 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
991 (const void *)&store_conv);
992 if (sshpam_err != PAM_SUCCESS)
993 fatal("PAM: failed to set PAM_CONV: %s",
994 pam_strerror(sshpam_handle, sshpam_err));
996 debug("PAM: establishing credentials");
997 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
999 debug("PAM: reinitializing credentials");
1000 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
1002 if (sshpam_err == PAM_SUCCESS) {
1003 sshpam_cred_established = 1;
1006 if (sshpam_authenticated)
1007 fatal("PAM: pam_setcred(): %s",
1008 pam_strerror(sshpam_handle, sshpam_err));
1010 debug("PAM: pam_setcred(): %s",
1011 pam_strerror(sshpam_handle, sshpam_err));
1015 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
1016 struct pam_response **resp, void *data)
1018 char input[PAM_MAX_MSG_SIZE];
1019 struct pam_response *reply;
1022 debug3("PAM: %s called with %d messages", __func__, n);
1026 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
1027 return (PAM_CONV_ERR);
1029 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1030 return (PAM_CONV_ERR);
1032 for (i = 0; i < n; ++i) {
1033 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1034 case PAM_PROMPT_ECHO_OFF:
1036 read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
1038 reply[i].resp_retcode = PAM_SUCCESS;
1040 case PAM_PROMPT_ECHO_ON:
1041 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1042 if (fgets(input, sizeof input, stdin) == NULL)
1044 if ((reply[i].resp = strdup(input)) == NULL)
1046 reply[i].resp_retcode = PAM_SUCCESS;
1050 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
1051 reply[i].resp_retcode = PAM_SUCCESS;
1058 return (PAM_SUCCESS);
1061 for(i = 0; i < n; i++) {
1062 free(reply[i].resp);
1065 return (PAM_CONV_ERR);
1068 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
1071 * XXX this should be done in the authentication phase, but ssh1 doesn't
1075 do_pam_chauthtok(void)
1078 fatal("Password expired (unable to change with privsep)");
1079 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1080 (const void *)&tty_conv);
1081 if (sshpam_err != PAM_SUCCESS)
1082 fatal("PAM: failed to set PAM_CONV: %s",
1083 pam_strerror(sshpam_handle, sshpam_err));
1084 debug("PAM: changing password");
1085 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
1086 if (sshpam_err != PAM_SUCCESS)
1087 fatal("PAM: pam_chauthtok(): %s",
1088 pam_strerror(sshpam_handle, sshpam_err));
1092 do_pam_session(struct ssh *ssh)
1094 debug3("PAM: opening session");
1096 expose_authinfo(__func__);
1098 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1099 (const void *)&store_conv);
1100 if (sshpam_err != PAM_SUCCESS)
1101 fatal("PAM: failed to set PAM_CONV: %s",
1102 pam_strerror(sshpam_handle, sshpam_err));
1103 sshpam_err = pam_open_session(sshpam_handle, 0);
1104 if (sshpam_err == PAM_SUCCESS)
1105 sshpam_session_open = 1;
1107 sshpam_session_open = 0;
1108 auth_restrict_session(ssh);
1109 error("PAM: pam_open_session(): %s",
1110 pam_strerror(sshpam_handle, sshpam_err));
1116 is_pam_session_open(void)
1118 return sshpam_session_open;
1122 * Set a PAM environment string. We need to do this so that the session
1123 * modules can handle things like Kerberos/GSI credentials that appear
1124 * during the ssh authentication process.
1127 do_pam_putenv(char *name, char *value)
1130 #ifdef HAVE_PAM_PUTENV
1134 len = strlen(name) + strlen(value) + 2;
1135 compound = xmalloc(len);
1137 snprintf(compound, len, "%s=%s", name, value);
1138 ret = pam_putenv(sshpam_handle, compound);
1146 fetch_pam_child_environment(void)
1152 fetch_pam_environment(void)
1154 return (pam_getenvlist(sshpam_handle));
1158 free_pam_environment(char **env)
1165 for (envp = env; *envp; envp++)
1171 * "Blind" conversation function for password authentication. Assumes that
1172 * echo-off prompts are for the password and stores messages for later
1176 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
1177 struct pam_response **resp, void *data)
1179 struct pam_response *reply;
1183 debug3("PAM: %s called with %d messages", __func__, n);
1187 if (n <= 0 || n > PAM_MAX_NUM_MSG)
1188 return (PAM_CONV_ERR);
1190 if ((reply = calloc(n, sizeof(*reply))) == NULL)
1191 return (PAM_CONV_ERR);
1193 for (i = 0; i < n; ++i) {
1194 switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
1195 case PAM_PROMPT_ECHO_OFF:
1196 if (sshpam_password == NULL)
1198 if ((reply[i].resp = strdup(sshpam_password)) == NULL)
1200 reply[i].resp_retcode = PAM_SUCCESS;
1204 len = strlen(PAM_MSG_MEMBER(msg, i, msg));
1206 buffer_append(&loginmsg,
1207 PAM_MSG_MEMBER(msg, i, msg), len);
1208 buffer_append(&loginmsg, "\n", 1);
1210 if ((reply[i].resp = strdup("")) == NULL)
1212 reply[i].resp_retcode = PAM_SUCCESS;
1219 return (PAM_SUCCESS);
1222 for(i = 0; i < n; i++) {
1223 free(reply[i].resp);
1226 return (PAM_CONV_ERR);
1229 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
1232 * Attempt password authentication via PAM
1235 sshpam_auth_passwd(Authctxt *authctxt, const char *password)
1237 int flags = (options.permit_empty_passwd == 0 ?
1238 PAM_DISALLOW_NULL_AUTHTOK : 0);
1241 if (!options.use_pam || sshpam_handle == NULL)
1242 fatal("PAM: %s called when PAM disabled or failed to "
1243 "initialise.", __func__);
1245 sshpam_password = password;
1246 sshpam_authctxt = authctxt;
1249 * If the user logging in is invalid, or is root but is not permitted
1250 * by PermitRootLogin, use an invalid password to prevent leaking
1251 * information via timing (eg if the PAM config has a delay on fail).
1253 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
1254 options.permit_root_login != PERMIT_YES))
1255 sshpam_password = fake = fake_password(password);
1257 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
1258 (const void *)&passwd_conv);
1259 if (sshpam_err != PAM_SUCCESS)
1260 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
1261 pam_strerror(sshpam_handle, sshpam_err));
1263 sshpam_err = pam_authenticate(sshpam_handle, flags);
1264 sshpam_password = NULL;
1266 if (sshpam_err == PAM_MAXTRIES)
1267 sshpam_set_maxtries_reached(1);
1268 if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
1269 debug("PAM: password authentication accepted for %.100s",
1273 debug("PAM: password authentication failed for %.100s: %s",
1274 authctxt->valid ? authctxt->user : "an illegal user",
1275 pam_strerror(sshpam_handle, sshpam_err));
1281 sshpam_get_maxtries_reached(void)
1283 return sshpam_maxtries_reached;
1287 sshpam_set_maxtries_reached(int reached)
1289 if (reached == 0 || sshpam_maxtries_reached)
1291 sshpam_maxtries_reached = 1;
1292 options.password_authentication = 0;
1293 options.kbd_interactive_authentication = 0;
1294 options.challenge_response_authentication = 0;
1296 #endif /* USE_PAM */